In recent years, battery devices are used in various products. When the amount of power to be used is large, the battery capacity also needs to be large. As the capacities of such battery devices are becoming larger, security and reliability are expected to be ensured.
As the capacities of battery devices become larger, the number of battery cells in each of the battery devices also becomes larger, and the price of each battery device becomes higher. Therefore, there is a possibility that a user takes apart a battery device, and replaces the internal battery cells with less expensive ones without authorization.
The applicant has previously suggested that IC chips should be provided in a battery device, and an identification number should be stored in each of the IC chips (Patent Document 1, for example). With this structure, the identification numbers are read from the battery device, and authenticating operations are performed based on the read identification numbers. In this manner, unauthorized battery devices can be spotted, and then be eliminated.